The present invention concerns a honeycomb body having stacked and/or wound sheet layers of which some of the sheet layers are structured sheet layers forming passages in which a fluid can flow. Honeycomb bodies of this kind are used for example for the catalytic conversion of exhaust gases of an internal combustion engine.
European Patent EP 0 436 533 B1 discloses honeycomb bodies which contain a stack, twisted in mutually opposite directions, of at least partially structured metal sheets in a tubular casing. One or more of the sheet layers of the stack is of greater thickness than the other layers, wherein the layer or layers contain or contains a thicker sheet or a plurality of thin sheets which bear closely against each other. The thicker and thinner sheet layers form walls of passages, through which the exhaust gas stream can flow. The sheet layers are connected to the tubular casing, at least in portions thereof, by a procedure involving intimate joining of the materials involved. The thicker sheet layers cannot be easily torn away at the tubular casing, by virtue of their greater mechanical strength. In addition they can also hold fast the thinner sheet layers which are adjacent thereto so that they also cannot be torn away from the tubular casing or however are held fast by the thick sheet layer at least in spite of being torn away at the tubular casing. The individual metal sheet layers of the stack can be soldered together, preferably at one of the two ends of the honeycomb body. The above-described configuration, by virtue of the thick sheet layers, affords a wall structure for stabilizing the honeycomb body.
In recent years the development of new honeycomb bodies has been along the lines of reducing thermal capacity. With a lower thermal capacity it is possible to achieve in particular improved cold start performance when using the honeycomb bodies in exhaust gas catalytic converters. The ignition temperature as from which the catalytic procedure begins is achieved earlier. Besides thermal capacity the pressure drop which occurs in a gas flow through the honeycomb body also plays a part in development. The pressure drop should be as low as possible. Both development aims, namely a low thermal capacity and a low pressure drop, can be achieved by the use of thin passage walls. However the passage walls cannot be made of just any arbitrarily thin dimension as the wall structure otherwise becomes unstable and is damaged under thermal and/or mechanical loadings.